1. Field of the Invention
The present invention relates to a method of controlling an image apparatus, and more particularly, to a method of controlling an imaging apparatus that images a region by dividing the region into a plurality of divided regions using an imaging device, and generates a large screen image by merging the divided regions.
2. Description of the Related Art
In a pathological field, a virtual slide apparatus that images and digitizes a sample placed on a slide so as to perform pathological diagnosis on a display is used as an alternative to an optical microscope. A conventional optical microscope image of a sample can be treated as digital data through digitization of pathological diagnosis by the virtual slide apparatus. Accordingly, it is possible to obtain the advantages of speeding up remote diagnosis, providing a description to a patient using a digital image, sharing rare cases, making education and practical training using such images more effective, and the like.
In order to realize an operation in an optical microscope using a virtual slide apparatus, the entire sample on a slide is required to be digitized. Digital data generated using the virtual slide apparatus through the digitization of the entire sample can be observed with viewer software operating in a personal computer (PC) or a workstation (WS). When the entire sample is digitized, the number of pixels is normally from hundreds of millions of pixels to billions of pixels, which is a very large amount of data. Therefore, in the virtual slide apparatus, the region of a sample is divided into a plurality of regions to be imaged using a two-dimensional imaging device that has from several hundreds of thousands of pixels to several millions of pixels, or a one-dimensional imaging device that has on the order of thousands of pixels. Since division imaging is performed, a plurality of divided images must be merged to generate an image of the entire sample.
As an alignment method when merging the divided images, there is a scheme of using feature extraction of joint portions and pattern matching by a correlation method. When image blur caused due to deviation of a sample in the depth of field or the like occurs in the joint portion (an area where a joint between two divided images is to be made), there is a problem that proper correspondence of features between the two divided images may not sufficiently be obtained, and thus alignment accuracy may deteriorate.
Japanese Patent Application Publication No. 2009-207188 discloses an imaging technology, that is, a so-called depth-of-field bracket function of adjusting a stop through a simple operation, changing the depth of field, and performing imaging. However, generation of a merged image using such images has not been disclosed.
There are known technologies for merging images, as disclosed in Japanese Patent Application Publication No. 2002-112095 and Japanese Patent Application Publication No. 2010-258885. Japanese Patent Application Publication No. 2002-112095 discloses technology that uses two exposure controls for this purpose, calculating an amount of position deviation using thinned images captured through exposure control by a second exposure control unit and generating a high dynamic range (HDR) image using the images captured through exposure control by a first exposure control unit. Japanese Patent Application Publication No. 2010-258885 discloses technology for extracting feature areas using reduced images, performing inter-image deviation amount detection between a plurality of images for which the exposure times are different and inter-image deviation correction using the feature areas, and generating an HDR image.
Japanese Patent Application Publication No. 2009-207188 discloses a technique for acquiring a focused image with improved contrast since a stop is narrowed so that the depth of field is deep and imaging is performed. However, generation of a merged image using such images has not been disclosed. The present inventors and others have studied a technique for acquiring images with improved contrast according to the method of Japanese Patent Application Publication No. 2009-207188 and performing merging based on the images. As a result, it can be understood that alignment of joint portions can be performed with good accuracy as a process of generating a merged image. However, it can be understood that there is a new problem, in that a high frequency component of the merged image is lost and resolution may deteriorate, since the stop is narrowed to perform the imaging.
According to the technologies for generating an HDR image, as disclosed in Japanese Patent Application Publication No. 2002-112095 and Japanese Patent Application Publication No. 2010-258885, an inter-image alignment process can be performed at high speed, since images are used for the inter-image alignment process separately from the HDR image. However, in such technologies, the advantage of improving alignment accuracy may not be obtained.